國産스테인레스鋼線系 矯正用線材의 開發과 物理的 性質에 關한 硏究

권오원,성재현,이기대,경희문 대한치과교정학회 1989 대한치과교정학회지 Vol.19 No.2

The physical properties of seven sizes of control groups and experimental group in stainless steel orthodontic wires were studied in tension, hardness, bending, torsion and observation of microstructure. The wires (0.40 - 0.90mm dia.) of round type were tested in the as-received condition. The wires of control groups were TRU-CHROME and REMANIUM, and experimental group was SK wire which was developed by ourselves and made in Korea. The results were as follows: 1. The chemical compositions of control groups and experimental group were austentie stainless steel wires of SOS 304. 2. Higher values of tensile and yield strength in tension were control group I, experimental group, control group II. Maximum tensile and yield strength of experimental group were 203.63 ±1.41kg/mm²in 0.70mm diameter and 148.96 ± 4.88kg/mm² in 0.60mm diameter, and maximum elongation was 5.20 ± 0.57% in 0.45mm diameter. 3. Hardness values of experimental group were similar to control groups. Maximum hardness values were 596.2 ± 13.66 Hv in 0.45mm diameter wire of control group I, 590.5 ± 20.08Hv in 0.50 mm diameter wire of control group II, and 563.6 ± 5.35 Hv in 0.70mm diameter wire of experimental group. 4. Torsion properties of experimental group were similar to control group I and more than control group II. Maximum torsion cycles were 31.8 ± 2.48 in 0.45mm diameter of control group I,17.4 ± 4.84 in 0.60mm diameter of control group II, and 24.6 ± 3.04 in 0.45mm diameter of experimental group. 5. Maximum bending cycles of experimental group were smaller than control groups. Maximum bending cycles were 9.00 ± 0.00 in 0.50mm diameter wire of control group I, 10.0 ± 0.82 in 0.40mm diameter wire of control group II, and 8.0 ± 1.26 in 0.50 mm diameter wire of experimental group. 6. Microstructures of experimental and control groups co-existed with martensited austenite structure and elongated austenite structure. 7. The direction of wire fracture was propagated parallel to torsion direction typically and there was no probability showing wire fracture at inclusions and surface scratches. 8. The type of wire fracture was brittle fracture at initiation site and ductile fracture at core.

신경회로망 제어기를 이용한 PID 파라미터 추정에 관한 연구

權重東,裵銀敬,金恩基,全基英,李承桓,吳鳳煥,李勳九,金容珠,韓慶熙 明知大學校 産業技術硏究所 2006 産業技術硏究所論文集 Vol.25 No.-

In this paper, supposed to solve these problem to PID parameters controller algorithm using ANN. In the proposed algorithm, the parameters of the controller were adjusted to reduce by on-line system the error of the speed of IM. In this process, EBPA NN was constituted to an output error value of an IM and conspired an input and output. The performance of the self-tuning controller is compared with that of the PH) controller tuned by conventional method (Ziehler-Nichols). The effectiveness of the proposed control method is verified thought the Matlab Simulink and experimental results.

Ni-Ti矯正用線材의 超彈性에 관한 硏究

權五源,徐惠敬,李基大 慶北大學校 齒科大學 1987 慶北齒大論文集 Vol.4 No.1

According to the development of the techniques for tooth movement, the research on the orthodontic wires has advanced and the Ni-Ti wire is highlighted these days. The Superelasticity of Ni-Ti wires was studied in tension. The wires were tested by universal testing machine. The elastic modulus was 20×10 exp (3)kg/㎟ in Cr-Ni wires, 21∼25×10(3)kg/㎟ in Co-Cr wires and 5∼6×10 exp (3)kg/㎟ in Ni-Ti wires. The elastic modulus of Ni-Ti wires was opproximately 1/4 of Cr-Ni wires and Co-Cr wires, and the elastic limit of Ni-Ti wires was approximately 4 times of Cr-Ni wires and Co-Cr wires. The permanent strain was approximately 0.5% in stress-strain curve of Ni-Ti wires.

齒科嬌正用線材의 物理的 性質에 미치는 熱處理의 影響

李基大,權五源,成材鉉 慶北大學校 齒科大學 1985 慶北齒大論文集 Vol.2 No.1

The physical properties of .016" orthodontic wires by heat treatment were studied in tension, bending, hardness and microstructures. The wires were tested in the as-manufactured and heat-treated conditions. The results were as follows: Ultimate tensile strength and yield strength were slightly increased by heat treatment, but Elgiloy was the most effective by geat treatment. The strength of Elgiloy showed the highest value after heat treatment above 6 minutes at 500, 600℃. Also, bending fluxure modulus of elasticity were progressively increased by heat treatment. the hardness number of Australian of as-manufactured wires showed the highest value, and Elgiloy showed the highest value by heat treatment. Microstructure of as-manufactured wires showed fibrous interlocking grains, and a coarse grains after heat treatment and an austenite structure after solution heat treatment.

구내 표준 방사선사진을 이용한 구내방사선촬영기의 선질 평가

이상섭,권혁락,심우현,오승현,이지연,전국진,김기덕,박창서 대한구강악안면방사선학회 2000 Imaging Science in Dentistry Vol.30 No.3

Purpose : This study was to evaluate the beam quality of intraoral X-ray equipments used at Yonsei University Dental Hospital (YUDH) using the half value layer (HVL) and the characteristic curve of intraoral standard X-ray film. Materials and Methods : The study was done using the intraoral X-ray equipments used at each clinical department at YUDH. Aluminum filter was used to determine the HVL. Intraoral standard film was used to get the characteristic curve of each intraoral X-ray equipment. Results : Most of the HVLs of intraoral X-ray equipments were higher than the least recommended thickness, but the REX 601 model used at the operative dentistry department and the X-707 model used at the pediatric dentistry department had HVLs lower than the recommended thickness. The slopes of the characteristic curves of films taken using the PANPAS 601 model and REX 601 model at operative dentistry department, the X-705 model of prosthodontic dentistry department, and the REX601 model at the student clinic were relatively low. Conclusion : HVL and the characteristic curve of X-ray film can be used to evaluate the beam quality of intraoral X-ray equipment. In order to get the best X-ray films with the least radiation exposure to patients and best diagnostic information in clinical dentistry, X-ray equipment should be managed in the planned and organized fashion. (Korean J Oral Maxillofac Radiol 2000; 30: 183-188)

대표적 근경류 생약의 방사선 방호효과

김성호,조성기,권오덕 대한방사선 방어학회 2001 방사선방어학회지 Vol.26 No.1

한의학에서 근경류(rhizomata)에 분류되어 있으며 각종 보익탕제에 주로 사용되는 대표적 생약인 백출(Baizhu, Atractylodes japonica), 천궁(Chuanxiong, Cnidium officinale), 산약(Shanyao, Discorea japonica) 및 승마(Shengma, Cimicifuga heracleifolia)의 방사선 방호효과를 확인하기 위해서 고선량 및 저선량의 방사선을 마우스에 조사하고 소장움 생존, 내재성 비장집락형성 및 apoptosis 유발 등을 관찰하였다. 방사선조사전 승마 투여군에서 소장움세포의 생존율을 증가시켰으며 내재성 비장집락 형성 시험에서는 천궁 투여군에서 평균치의 증가가 관찰되었고 천궁 및 승마는 저선량 방사선에 의한 apoptosls 형성을 억제시켰다. 이상의 결과에서 승마 및 천궁의 방사선 방호효과를 조혈세포의 생존과 회복, 소장움세포 생존을 통하여 확인하였으며 이는 독성이 적은 천연물이라는 관점에서 방사선 방호 식품으로서 적용이 가능할 것으로 사료된다. We performed this study to determine the effect of Baizhu(Atractylodes japonica), Chuanxiong(Cnidium officinale), Shanyao(Discorea japonica) and Shengma(Cimicifuga heracleifolia), as Oriental rhizomata herbs, on jejunal crypt survival, endogenous spleen colony formation and apoptosis in jejunal crypt cells of mire irradiated with high and low dose of γ-radiation. Shengma was effective in intestinal crypt survival(p<0.05). The frequency of radiation induced apoptosis was also reduced by pretreatment with Chuanxiong and Shengma(p<0.05). Although the mechanisms of this effect remain to be elucidated, these results indicated that Shengma might be a useful radioprotector, especially since it is a relatively nontoxic natural product.

Electroabsorption modulator-integrated distributed Bragg reflector laser diode for C-band WDM-based networks

Oh-Kee Kwon,Chul-Wook Lee,Ki-Soo Kim Electronics and Telecommunications Research Instit 2023 ETRI Journal Vol.45 No.1

We report an electroabsorption modulator (EAM)-integrated distributed Bragg reflector laser diode (DBR-LD) capable of supporting a high data rate and a wide wavelength tuning. The DBR-LD contains two tuning elements, plasma and heater tunings, both of which are implemented in the DBR section, which have blue-shift and red-shift in the Bragg wavelength through a current injection, respectively. The light created from the DBR-LD is intensity-modulated through the EAM voltage, which is integrated monolithically with the DBRLD using a butt-joint coupling method. The fabricated chip shows a threshold current of approximately 8 mA, tuning range of greater than 30 nm, and static extinction ratio of higher than 20 dB while maintaining a side mode suppression ratio of greater than 40 dB under a window of 1550 nm. To evaluate its modulation properties, the chip was bonded onto a mount including a radiofrequency line and a load resistor showing clear eye openings at data rates of 25 Gb/s nonreturn-to-zero and 50 Gb/s pulse amplitude modulation 4-level, respectively.

A <tex> $10 \times 10$</tex>-Gb/s DFB-LD Array Integrated With PLC-Based AWG for 100-Gb/s Transmission

Oh Kee Kwon,Young-Tak Han,Young Ahn Leem,Jang-Uk Shin,Chul Wook Lee,Ki Soo Kim IEEE 2014 IEEE photonics technology letters Vol.26 No.21

<P>We describe a hybrid integration module of a 10 × 10-Gb/s distributed feedback laser diode array (DFB-LDA) and a planar light-wave circuit-based arrayed waveguide grating (AWG). For fabrication of the DFB-LDA, we adopted a selective area growth technique to tailor the channel gain properly, and E-beam lithography to accurately control the channel lasing wavelength and grating phase. For implementation of the AWG, we introduced a 2%-Δ structure to reduce the coupling loss between the AWG and DFB-LDA, and designed the tapered and parabolic waveguides at the junctions of the free propagation regions to widen the spectral passband width (i.e., a -1-dB spectral width of 3 nm). The developed module shows a side-mode suppression ratio of >45 dB, a clear eye opening with a dynamic extinction ratio of >4.4 dB at 10 Gb/s, and a power penalty of <;1.5 dB after a 2-km transmission for all channels.</P>

The effect of gain medium length on dynamic mode stability in semiconductor lasers with a long intra-cavity filter

Kwon, Oh Kee,Lee, Chul Wook,Shin, Jang Wook,Sim, Eun Deok,Kim, Jong-Hoi,Lee, Dong Hun,Bang, Dong Soo,Baek, Yong Soon The Optical Society 2009 Optics express Vol.17 No.25

<P>We investigate theoretically and experimentally the effect of the physical length of gain medium on dynamic mode stability in semiconductor lasers with an intra-cavity filter. In simulation, two types of analysis models were used to examine the lasing properties and to analyze the dynamic mode stability of the external-cavity system, respectively. In experiment, two different kinds of the structures were fabricated and their spectra were analyzed. Both simulation and measurement results show clearly the length of the gain medium has a critical influence on the stability around the peak wavelength of the filter.</P>

Effects of Somatotropinand Human Vascular Endothelial Growth Factor on the In Vitro Development of Porcine Oocytes using Chemically Defined Medium

Kwon, Oh-Seo,Koo, Ok-Jae,Kwon, Dae-Kee,Kang, Jung-Taek,Oh, Hyun-Joo,Hong, So-Gun,Park, Jung-Eun,Park, Hee-Jung,Kim, Dae-Yong,Lee, Byeong-Chun 한국수정란이식학회 2006 한국수정란이식학회 학술대회 Vol.2006 No.1